Field of the Invention
The present invention relates to a technique for supplying solder to a mask sheet.
Description of the Background Art
Japanese Patent Application Laid-Open No. H7-205403 discloses an apparatus which constantly detects the rolling diameter of cream solder during a process of printing the cream solder to determine the insufficiency or excess of the amount of the cream solder and which, in the case of insufficiency, replenishes the amount of cream solder equivalent to the insufficiency, and in the case of excess, removes the excess amount of cream solder.
However, the area of openings formed in a mask sheet varies at each point in an X direction that is a lengthwise direction of a squeegee, and thus, the amount of decrease in solder amount associated with the printing process varies at each point in the X direction. The apparatus adjusts the amount of solder by determining the insufficiency or excess of the solder amount using the measurement result obtained at only one measurement position. Thus, the apparatus fails to sufficiently adjust the amount of solder at another position where the measurement is not carried out.
Furthermore, if the moving range of a head is short compared to the length of the squeegee, making the amount of solder supplied uniform at each point in the X direction disadvantageously increases the number of solder rolling operations. Thus, there has been a demand for measures against this problem.